plane/apps/app/styles/editor.css

.empty-node::after {
  content: attr(data-placeholder);
  color: #9ca3af;

  position: absolute;
  pointer-events: none;
  top: 15px;
  margin-left: 1px;
}

.ProseMirror {
  position: relative;
  word-wrap: break-word;
  white-space: pre-wrap;
  -moz-tab-size: 4;
  tab-size: 4;
  -webkit-user-select: text;
  -moz-user-select: text;
  -ms-user-select: text;
  user-select: text;
  outline: none;
  cursor: text;
  line-height: 1.2;
  font-family: inherit;
  font-size: 14px;
  color: inherit;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  appearance: textfield;
  -webkit-appearance: textfield;
  -moz-appearance: textfield;
}

.ProseMirror-icon {
  display: inline-block;
  line-height: 0.8;
  vertical-align: -2px;
  color: #666;
  cursor: pointer;
  margin: 0 3px;
  padding: 3px 8px;
  border-radius: 3px;
  border: 1px solid transparent;
  transition: background 50ms ease-in-out;
  -moz-user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.ProseMirror-menu-disabled.ProseMirror-icon {
  opacity: 0.3;
  cursor: default;
  pointer-events: none;
}

.ProseMirror-icon svg {
  fill: currentColor;
  height: 1em;
}

.ProseMirror-icon span {
  vertical-align: text-top;
}

.remirror-editor-wrapper .remirror-editor {
  min-height: 150px;
}

.issue-comments-section .remirror-editor-wrapper .remirror-editor,
.page-block-section .remirror-editor-wrapper .remirror-editor {
  min-height: 50px;
}

.remirror-section .remirror-editor-wrapper .remirror-editor {
  min-height: 0 !important;
}

.remirror-editor-wrapper {
  padding-top: 8px;
}

.MuiButtonBase-root {
  border: none !important;
  border-radius: 0.25rem !important;
  padding: 0.25rem !important;
}

.MuiButtonBase-root svg {
  fill: rgb(var(--color-text-base)) !important;
}

.MuiButtonBase-root.Mui-selected,
.MuiButtonBase-root:hover {
  background-color: rgb(var(--color-bg-base)) !important;
}